Method of determining whether an improved item has a better mean lifetime than an existing item

a technology of improved items and mean lifetimes, applied in the field of life testing applications, can solve the problems of remarkable statistical power and not widely known existing methods, and achieve the effect of preserving reasonable levels of statistical power and reducing cost and time on tes

Inactive Publication Date: 2006-03-07
UNITED STATES OF AMERICA THE AS REPRESENTED BY THE SEC OF THE ARMY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Benefits of technology

[0007]The method reduces cost and time on test w...

Problems solved by technology

However, existing methods are not widely kno...

Method used

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  • Method of determining whether an improved item has a better mean lifetime than an existing item
  • Method of determining whether an improved item has a better mean lifetime than an existing item
  • Method of determining whether an improved item has a better mean lifetime than an existing item

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example

[0026]A current light bulb has a well defined mean life of 1000 hours and is adequately described by the exponential random variable with parameter 1 / 1000. An experimenter wants to show that a new light bulb has higher mean life. The experimenter places n=35 new versions of light bulb on life test and notes the following failure times. The first bulb fails at time 49 hours, the second at time 72 hours, the third at time 115 hours, and the fourth at time 197 hours. Using a PC jointly running MAPLE, APPL and “CensoredT,” after the first bulb failure, the experimenter enters the failure time into a list of failure times and executes the CensoredT command to determine that the statistical P-value for only one failure is 0.255. After the second failure, the experimenter enters the new failure time into the list of previously noted failure times and re-executes the CensoredT command to determine that the statistical P-value for both of the two items is 0.203. After the third failure, the ...

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Abstract

A method of determining whether an improved item has a better mean lifetime than an existing item having a fully specified lifetime distribution function. A finite number n of examples of the new item are placed on life test, and the failure times of the n examples of the new item are recorded as they occur. At each occurrence of failure, the newly noted failure time is entered into a list of previously noted failure times and the most up-to-date statistical P-value is calculated for the life test so far. When the statistical P-value is sufficiently small there is statistical inference that the new item is better than the current one, and the test is ended.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims priority from U.S. Provisional Patent Application Ser. No. 60 / 510,517 filed Oct. 14, 2003.BACKGROUND OF THE INVENTION[0002]This invention relates in general to life testing applications, and more particularly to tests designed to gain an understanding of the probabilistic properties of a component or a system of components.[0003]Consider an existing component, process, or a pharmaceutical drug with a fully specified lifetime distribution function F(x). Should an improved component, process, or pharmaceutical drug come along, both producers and consumers would like to verify that the new item compares favorably to the existing item, most often by determining if its mean lifetime has decreased or increased.[0004]In the life testing of the new component, it would be highly desirable, in terms of money and time, to stop the test when enough evidence exists to support a claim that the mean lifetime has either decreased ...

Claims

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Application Information

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IPC IPC(8): G06F11/30G06F9/45
CPCG06F11/008
Inventor GLEN, ANDREW G.FOOTE, BOBBIE L.
Owner UNITED STATES OF AMERICA THE AS REPRESENTED BY THE SEC OF THE ARMY
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